| Objective:The occurrence of abortion is very common in the population,and the incidence of recurrent abortion is about 2%-3%.The causes of recurrent miscarriages are complex and diverse.One of the most common causes is chromosomal abnormalities.This study aims to investigate and type the source of abnormal chromosomes,and according to the typing results,select patients with similar phenotypes to perform the Whole Exome Sequencing to clarify whether they carry mutations of the same gene or genes that are related to meiosis and mutations in the same pathway.Methods: Villus tissues that were aborted and peripheral blood of both spouses were collected and the medical history was recorded.According to the medical history,the study subjects were divided into the one-time spontaneous abortion group and the recurrent spontaneous abortion group.The incidence and spectrum of chromosomal abnormalities were analyzed in two groups.In addition,short tandem repeats(STR)were employed as markers of chromosomes,and five STR were typed on the collected aborted villus and peripheral blood DNA samples.According to the results of STR analysis,patients with similar phenotypes were selected for whole exome sequencing,and the whole exome sequencing results were analyzed in order to finding candidate genes.Results: A total of 122 spontaneous abortions tissues were recruited and the incidence and spectrum of villous chromosome abnormalities were analyzed.This study found that the abnormality rate of chromosome of villous in RSA group was slightly lower than that in one-time abortion group.Among them,there were more numerical abnormalities than structural ones.Among numerical abnormalities,trisomy 13,16,21,and 22,and triploid and X monomer abnormalities were more common.There are differences in the spectrum of chromosomal abnormalities in patients with single and repeated abortions.Trisomy 16 is more common in patients with one-time abortion,and trisomy 22 was more common in patients with recurrent abortion.In the analysis of the origin of abnormal chromosomes,we found that for chromosome trisomy of the villous,the chromosome separation error was the most common while the oocyte divides for the first meiosis;among the 45,X monomers,that the paternal X chromosome lost were common,while the maternal X chromosome were retained.For triploid,there were one more set of paternal chromosomes than that of maternal chromosomes.Based on the above STR typing results,we collected 5 patients with recurrent abortions for whole exome sequencing.Through the analysis of whole exome sequencing results,eight proteins encoding candidate genes known to be involved in cell cycle regulation,meiosis,germ cell maturation,and DNA mismatch repair as CCNA1(MIM:604036)、WAPL(MIM:610754)、SGO2(MIM:612425)、STRA8(MIM:609987)、AR(MIM:313700)、EXO1(MIM:606063)、MSH2(MIM: 609309)、MLH1(MIM:120436)were screened out.Conclusions: The incidence and spectrum of villous chromosome abnormalities in one-time spontaneous abortion and recurrent miscarriage are different.Trisomy 16 is more common in the former,and trisomy 22 is more common in the latter.This indicates that a villous chromosome abnormality gave an important signal for the outcome of the next pregnancy.This signal provides a new idea for the clinical understanding of embryo chromosome abnormality.At the same time,through whole exome sequencing,we found some mutations of genes which related to cell cycle regulation,meiosis,germ cell maturity,and DNA mismatch repair and recombination,which may be involved in the occurrence of abnormal villous.The results provide a direction and consideration for the etiology of spontaneous abortion.It will be beneficial for etiology research of miscarriage prevention and treatment,and provide a basis for exploring the relationship between meiotic errors and abortion. |
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